Image-guided tumor therapy through thermal ablation is now the predominant choice for treating early-stage solid tumors. Currently, the most popular ablation method is radiofrequency (RF) ablation, which is based on the same principle as electrocautery. However, larger tumors are difficult to treat with RF because of its self- limiting heating mechanism and susceptibility to the cooling effect of nearby vasculature. Recent studies from our lab have shown that microwave ablations are capable of overcoming this heat-sink effect and providing a more consistent ablation zone. But the added benefit of better ablative margins comes at the cost of the potential of vascular damage and thrombosis. The aim of this study is to model the heating effects of microwave energy near blood vessels and correlate the damage from these vessels to the risk of thrombosis through a cost function. We will use numerical modeling analysis to perform a parametric study on a heated vessel, isolating the physiologically-relevant range of vessel diameters, blood flow rates and distances from the ablation zone which can lead to cytotoxic heat transfer (Aim 1). We will then validate the simulation results with a phantom vessel model, incorporating clinical components such as real blood and microwave applicators (Aim 2). Lastly, we will perform ablations near vessels using in-vivo models, allowing us to analyze cytotoxic heat transfer in a complex, clinically-relevant environment (Aim 3). Completion of this project will lead to better understanding of coupling electromagnetic analysis with thermal flow, blood viscosity changes in a high-temperature environment and endothelial damage near microwave ablation zones. The goal of this project is to use the data from the three aims to create a thrombotic risk function. This function will allow physicians to safely guide the placement of a microwave ablation applicator to minimize the risk for a thrombotic event. We will primarily using the liver as our organ of interest, but the data we plan to compile will be clinically useful for the ablation of any solid tumor. As with many of our studies in the past, the proposed work is designed to directly influence patient care in tumor ablation programs world-wide.